In order to begin a combustion process inside a fossil fuel fired combustion chamber, such as that found in industrial and utility boilers, an energy source, such as a gas pipe ignitor is required to begin a self-sustaining combustion reaction of main fuel and air.
Ignitors generally have a dedicated fuel and air supply, a flame ignition source, and a flame detector. In operation, fuel and air are introduced to the ignitor and the ignition source provides a spark to begin a self-sustaining reaction that keeps the ignitor burning. The flame detector provides proof that the ignitor is operating.
In a combustion chamber, such as a tangential or a wall fired boiler, ignitors can be mounted to structural elements. For example, in a tangential boiler, pulverized coal and air are introduced into a furnace through fuel-air admission assemblies disposed in structural elements called windboxes located in the corners of the furnace. Auxiliary fuel burners, which includes an ignitor disposed within a moveable air nozzle, are also located in the windboxes, proximate to the fuel-air assemblies. The auxiliary fuel burners and fuel-air assemblies are aimed tangentially to an imaginary circle in the middle of the furnace to create a fireball, which serves as source of ignition for the incoming coal. A distinct advantage of the tangential firing boiler is that steam temperature can be controlled by tilting in unison the fuel-air admission assemblies and auxiliary fuel burners of the individual windbox upward or downward. By doing so, the fireball is physically raised or lowered within the furnace, which increases or decreases the heat absorption by the water walls in the furnace. An example of a tangential boiler is disclosed in U.S. Pat. No. 4,434,747.
Ignitors use a wide variety of gas and oil fuels, and selection of fuels usually depends on availability and costs. Due to cost considerations, combustion facilities with oil ignitors disposed in moveable structural elements have attempted to convert to gas pipe ignitors with limited success. Current gas pipe ignitors are rigid, which when coupled to a movable nozzle tip, limits the directional movement and control of the nozzle tip. While attempts have been made to modify moveable nozzle tips to accommodate a rigid gas pipe ignitor, such modifications have drawbacks. For example, one such modification includes insertion of slots into directional blades of the nozzle tip in order to allow the nozzle tip to tilt upward and downward while rigid gas pipe ignitor remains stationary. A disadvantage of such a modification of the nozzle tip includes reduced effectiveness of nozzle tips.